Beam receiving system by frequency multiplication



NOV. 14, 1933. l J. PLEBANSK| 1,935,375

BEAM RECEIVING SYSTEM BY FREQUENCY MULTIPLICATION Filed Feb. 17, 1930 BYLQ 69M rae-.nad Nev. i4, i933 Vriant 1,935,375 anar/i anonivincsivs'rnin er FnEQUcNcr 'rrrLroA'rroN v ,A

Jozef Plebanski, Warsaw,' Poland, assignor 'to Radio Corporation of'America, New York,

N. Y., a corporation of Delaware Y Applicatin February i7, 1930, serialNo. 428,998, and in )Poland March, 1329' A 'I This invention relates' todirective antenna systems, and more particularly to'such of these whichutilize a plurality of aerials, suitably spaced apart, forreceiving'pur'poses.

It is well known in the art that spacing between the individual aerialsof such directive-receiving systems is a factor which depends upon theWave length `of the signal to be received.'

, `'I'hesesysterns are usually designed to receive with high efciencysignals incoming from one direction and to discriminate against signalsfrom other directions. Such result is effected by making the phases of'the. currents. induced inl the system by the signal incoming from thedesired direction additive in character so as to give maximum currentdensity while making the phases of the currents induced by signals fromother undesired directions opposite in character'so as to cancel out. y

The invention is more fully described in connection with theaccompanying drawing wherein,

Figure 1 diagrammatically illustrates a pair of vertical antenna andVarious directions of waves impinging thereon,

Figure 2 illustrates one form of the present invention,

Figure 3 is a diagram illustrating the operation of the apparatus shownin Figure 2,

Figure 4 illustrates an embodiment of my invention utilizing four spacedantennae,

Figure 5 is a characteristic curve of my arrangement shown in Figure 4,and,

Figure 6 illustrates a modification of my in- Vention wherein receivedwaves are obtained to lower intermediate frequencies before beingfrequency multiplied.

Referring to Figure 1 of the drawing, there are shown two antennas A andBspaced apart a distance d. For a wave being received from direction Ithe currents induced in A and B will be in phase, the resulting totalcurrent being twice as great as the current in either one of the twoantennas.

On the other hand, for a wave incoming from direction III in the planeof the two antennas,

there will be a phase difference in the currents in-, duced in A and Bwhich may be represented by the equation Y 21rd t T y where d is theantenna spacingV and A the wave length. If, now, the spacing is madeequal to a half wave length iigure then ,4) will equal 180"` Yand thesum ofthe currents in the two antennas will be Zero. Similarly, if ffdequals gigqb will'equal or 22 Y3Q and the; surn` of thecurrents inducedby thesignal coming from'direction III will not be zero... u

But if we arrange the two antennas according to the Fig. 2 andfby meansof arbitrary frequency changersA (frequency 'transformers orvalvefrequencyv changers) westep up the frequency 48k times (i. ertimesydoubling the frequency) `then we can prove, that the phase differencebetween currents in anodes of the valves lc, Z will be 8 times greaterthan direct in antennas I kand II.

If we have for instance square law detectors,

then the detector current can be shown by the Aif e=uA sin (wt+)+B sinpt sin (wt-agb).

AB sin ptrcos @wt-eht] From the above it is clear that by frequencydoubling the phaseshiiting is also doubled.

It can be proved, that if we have any frequency changing arrangementwhich increases the frequency 2, 3 n times then the phaseshifting(relative phase) will also be increased 2, 3 11. times. g

Therefore spacing aerials for instance at c1=s and increasing thefrequency according to Fig. 2-8 times we can get the same directionalcharacteristics, as with spacing of aerials, but saving much room. l

By combining according to Fig. 2 two directional systems having eachcardioid reception diagram (Fig. 3) we can get an improvedcharacteristie sho-wn by 1 and 2 on Fig. 3. l.

In this way any systems (or aerials) nondirective or directional` can becombined and the di-v rectional characteristic can be improved.

Therefore by adequate spacing the used wavelength can be too short. l

To obviate this, we can utilize the superhetero dyne principle and rstof all change the incoming signal to the greater wavelengthl (Fig. 6).

The used heterodyne (one or more) ,can feed roo all circuits at the sametime. The intermediate l Y Wavelength can then be reduced (frequencyincreased) by means of frequency changers. The directional results Willbe the same as above, but the construction will be much plainer andeasier. Adjust-ing the phases of heterodyne 'toea'ch circuit separatelythe beam can be rotated.

The increased intermediate frequency 'can be stepped up to the (ab)original Wavelength of signal and then regeneration may be utilized asindicated in Fig. 6. f

Referring to Figure 6 in more detail, 'it will -be seen that theintermediatev frequency .can be stepped up to the same amounta'svb'efore hetero'- dyning to obtain a frequency Which may Abe.represented by the equationr2(V-TV0)K=V, Where V is the .signalfrequency and A'Vo the -heterordyne frequency. For example, for asignalfrequency of 800 kc and heterodynefrequency of .'700 kc then V-VczlOO kcand 2 (100)=23 G00) :800 kc. From the foregoing, it will be seen thatfor three times frequency doubling (2 '2 2=`8 times) :of the'intermediate tfrequency 1'00 V`kc, there is obtained the same frequencyas the original. This frequency can :be used to regenerate thereceiverrupon the input side. Of course, the multiplied-'outputfrequency must v'ibe the same or about fthesame fas the original:sig-nal frequency.

Only in this case, this method of regeneration or reaction fmay'beused.'By using this kind -cf reaction on each antenna al'stillfb'etterdirectional characteristic 'is obtained. In Figure 16 such arrangementis shown with only twoantennas. rOf course, any vnumber kof .antennasmay be used.

Each antenna or antenna system is associated with one receiver in whichthe signal frequency is reduced by means of a heterodyne Vu to theintermediate frequency V-Vo Which is then multipled by means'of valvesor other arrangements between points c, d and-c d" until va. frequency2n Y (V-Vo) is obtained, and if this frequency is equal to 'the signalfrequency V it may be used for regeneration purposes. The combinedoutput is fed to the peints c, b.

In this Way less quantity ofvalves can be used.

Furthermore the antennas from Fig. 4 can be for linstance combined-rstly every two then every three and finally the sum current of allfour can `'beit-alien.

l Using this kind of intercombination with frequency multiplicationstill better directional characteristics can be got.

With :five antennas for instance al1 1A; A wide by ysuitable combiningand frequency multiplication the same Adirectional `characteristic canbe got as with '1'01/2 A Wide beam :receiving aerial.

- What iisclaimedis: v 'I In a radio receiving system, a :plurality ofspaced rantennae,'means for heterodyning 'the 'A eratively amplifying,said frequency multiplied energy, .and means for .combiningthefrequency multiplied .energy whereby "the directive charac-- isimproved.

teristic fof saidV antenn y JOZEF PLEBANSKI.

